There are needs in many contexts for a safety catch for interconnecting two parts, in which the safety catch, on being subjected to counter-directed traction forces exceeding a given magnitude, breaks the interconnection between the two parts and thereby releases the interconnected parts from one another. Such needs are particularly accentuated in practical applications in which there may be the risk of injury, for example personal injury, if the forces involved become excessively large. Such may, for instance, be the case in connection with sport and freetime activities such as, for example, skiing. There is also a need in buckles for children's safety helmets, that the buckles disengage if the traction forces in the straps retaining the helmet on the child's head become excessive. Accidents have occurred because children wearing such safety helmets while playing in, for example, trees have become trapped by the helmet between two branches of a tree, been unable to escape by their own efforts and consequently been strangled.
There are also needs to be able, in the buckles employed for safety helmets to adjust that force at which the parts interconnected by the buckle are released from one another. In, for instance, children's helmets, such release force may thereby be adapted to meet relevant requirements, and the helmet be thus rendered usable and operate with completely adequate function irrespective of the weight of the child.